/* Copyright  (c) 2002 Graz University of Technology. All rights reserved.
 *
 * Redistribution and use in  source and binary forms, with or without 
 * modification, are permitted  provided that the following conditions are met:
 *
 * 1. Redistributions of  source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in  binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *  
 * 3. The end-user documentation included with the redistribution, if any, must
 *    include the following acknowledgment:
 * 
 *    "This product includes software developed by IAIK of Graz University of
 *     Technology."
 * 
 *    Alternately, this acknowledgment may appear in the software itself, if 
 *    and wherever such third-party acknowledgments normally appear.
 *  
 * 4. The names "Graz University of Technology" and "IAIK of Graz University of
 *    Technology" must not be used to endorse or promote products derived from 
 *    this software without prior written permission.
 *  
 * 5. Products derived from this software may not be called 
 *    "IAIK PKCS Wrapper", nor may "IAIK" appear in their name, without prior 
 *    written permission of Graz University of Technology.
 *  
 *  THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESSED OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 *  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 *  PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE LICENSOR BE
 *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
 *  OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 *  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
 *  OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 *  ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 *  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 *  OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 *  POSSIBILITY  OF SUCH DAMAGE.
 */

package demo.pkcs.pkcs11;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.math.BigInteger;
import java.security.MessageDigest;
import java.util.Arrays;

import iaik.pkcs.pkcs11.Mechanism;
import iaik.pkcs.pkcs11.Module;
import iaik.pkcs.pkcs11.Session;
import iaik.pkcs.pkcs11.Slot;
import iaik.pkcs.pkcs11.Token;



/**
 * This demo program uses a PKCS#11 module to calculate a hash of a given file.
 * Optionally the calcualted raw hash can be written to file. The program also
 * verifies the calculated hash with a software hash from Java.
 *
 * @author <a href="mailto:Karl.Scheibelhofer@iaik.at"> Karl Scheibelhofer </a>
 * @version 0.1
 * @invariants
 */
public class Digest {

  public static void main(String[] args) {
    if ((args.length != 3) && (args.length != 4)) {
      printUsage();
      System.exit(1);
    }

    try {

        Module pkcs11Module = Module.getInstance(args[0]);
        pkcs11Module.initialize(null);

        Slot[] slots = pkcs11Module.getSlotList(Module.SlotRequirement.TOKEN_PRESENT);

        if (slots.length == 0) {
          System.out.println("No slot with present token found!");
          System.exit(0);
        }

        Slot selectedSlot = slots[0];
        Token token = selectedSlot.getToken();

        Session session =
            token.openSession(Token.SessionType.SERIAL_SESSION, Token.SessionReadWriteBehavior.RO_SESSION, null, null);

        // login user
        //session.login(Session.UserType.USER, args[1].toCharArray());

        System.out.println("################################################################################");
        System.out.println("digesting data from file: " + args[2]);


        //be sure that your token can process the specified mechanism
        Mechanism digestMechanism = Mechanism.SHA_1;

        byte[] dataBuffer = new byte[4096];
        byte[] helpBuffer;
        int bytesRead;
        
        FileInputStream dataInputStream = new FileInputStream(args[2]);
        
        int updateCounter = 0;
        long t0 = System.currentTimeMillis();

        // initialize for digesting
        session.digestInit(digestMechanism);
        // feed in all data from the input stream
        while ((bytesRead = dataInputStream.read(dataBuffer)) >= 0) {
          if (bytesRead < dataBuffer.length) {
            helpBuffer = new byte[bytesRead]; // we need a buffer that only holds what to send for digesting
            System.arraycopy(dataBuffer, 0, helpBuffer, 0, bytesRead);
            session.digestUpdate(helpBuffer);
          } else {
            session.digestUpdate(dataBuffer);
          }
          updateCounter++;
        }
        byte[] digestValue = session.digestFinal();
        
        long t1 = System.currentTimeMillis();

        dataInputStream.close();        

        Arrays.fill(dataBuffer, (byte) 0); // ensure that no data is left in the memory
        
        System.out.println("The digest value is: " + new BigInteger(1, digestValue).toString(16));
        System.out.println("Calculation took " + (t1 - t0) + " milliseconds using " + updateCounter + " update calls.");

        if (args.length == 4) {
          System.out.println("Writing digest value to file: " + args[3]);

          FileOutputStream signatureOutput = new FileOutputStream(args[3]);
          signatureOutput.write(digestValue);
          signatureOutput.flush();
          signatureOutput.close();
        }
  
        System.out.println("################################################################################");


        System.out.println("################################################################################");
        System.out.println("verifying digest with software digest");

        MessageDigest softwareDigestEngine = MessageDigest.getInstance("SHA-1");

        dataInputStream = new FileInputStream(args[2]);

        updateCounter = 0;
        t0 = System.currentTimeMillis();
        
        // feed in all data from the input stream
        while ((bytesRead = dataInputStream.read(dataBuffer)) >= 0) {
          softwareDigestEngine.update(dataBuffer, 0, bytesRead);
          updateCounter++;
        }
        byte[] softwareDigestValue = softwareDigestEngine.digest();

        t1 = System.currentTimeMillis();
        
        dataInputStream.close();
        
        Arrays.fill(dataBuffer, (byte) 0); // ensure that no data is left in the memory

        System.out.println("The digest value is: " + new BigInteger(1, softwareDigestValue).toString(16));
        System.out.println("Calculation took " + (t1 - t0) + " milliseconds using " + updateCounter + " update calls.");
        
        if (Arrays.equals(digestValue, softwareDigestValue)) {
          System.out.println("Verified Message Digest successfully");
        } else {
          System.out.println("Verification of Message Digest FAILED");
        }

        System.out.println("################################################################################");


        session.closeSession();
        pkcs11Module.finalize(null);

    } catch (Throwable thr) {
      thr.printStackTrace();
    }
  }

  public static void printUsage() {
    System.out.println("Usage: Digest <PKCS#11 module> <user-PIN> <file to be digested> [<digest value file>]");
    System.out.println(" e.g.: Digest pk2priv.dll password data.dat digest.bin");
    System.out.println("The given DLL must be in the search path of the system.");
  }

}